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-rw-r--r--src/shader_recompiler/frontend/maxwell/indirect_branch_table_track.cpp108
1 files changed, 108 insertions, 0 deletions
diff --git a/src/shader_recompiler/frontend/maxwell/indirect_branch_table_track.cpp b/src/shader_recompiler/frontend/maxwell/indirect_branch_table_track.cpp
new file mode 100644
index 000000000..008625cb3
--- /dev/null
+++ b/src/shader_recompiler/frontend/maxwell/indirect_branch_table_track.cpp
@@ -0,0 +1,108 @@
+// Copyright 2021 yuzu Emulator Project
+// Licensed under GPLv2 or any later version
+// Refer to the license.txt file included.
+
+#include <optional>
+
+#include "common/common_types.h"
+#include "shader_recompiler/exception.h"
+#include "shader_recompiler/frontend/maxwell/decode.h"
+#include "shader_recompiler/frontend/maxwell/indirect_branch_table_track.h"
+#include "shader_recompiler/frontend/maxwell/opcodes.h"
+#include "shader_recompiler/frontend/maxwell/translate/impl/load_constant.h"
+
+namespace Shader::Maxwell {
+namespace {
+union Encoding {
+ u64 raw;
+ BitField<0, 8, IR::Reg> dest_reg;
+ BitField<8, 8, IR::Reg> src_reg;
+ BitField<20, 19, u64> immediate;
+ BitField<56, 1, u64> is_negative;
+ BitField<20, 24, s64> brx_offset;
+};
+
+template <typename Callable>
+std::optional<u64> Track(Environment& env, Location block_begin, Location& pos, Callable&& func) {
+ while (pos >= block_begin) {
+ const u64 insn{env.ReadInstruction(pos.Offset())};
+ --pos;
+ if (func(insn, Decode(insn))) {
+ return insn;
+ }
+ }
+ return std::nullopt;
+}
+
+std::optional<u64> TrackLDC(Environment& env, Location block_begin, Location& pos,
+ IR::Reg brx_reg) {
+ return Track(env, block_begin, pos, [brx_reg](u64 insn, Opcode opcode) {
+ const LDC::Encoding ldc{insn};
+ return opcode == Opcode::LDC && ldc.dest_reg == brx_reg && ldc.size == LDC::Size::B32 &&
+ ldc.mode == LDC::Mode::Default;
+ });
+}
+
+std::optional<u64> TrackSHL(Environment& env, Location block_begin, Location& pos,
+ IR::Reg ldc_reg) {
+ return Track(env, block_begin, pos, [ldc_reg](u64 insn, Opcode opcode) {
+ const Encoding shl{insn};
+ return opcode == Opcode::SHL_imm && shl.dest_reg == ldc_reg;
+ });
+}
+
+std::optional<u64> TrackIMNMX(Environment& env, Location block_begin, Location& pos,
+ IR::Reg shl_reg) {
+ return Track(env, block_begin, pos, [shl_reg](u64 insn, Opcode opcode) {
+ const Encoding imnmx{insn};
+ return opcode == Opcode::IMNMX_imm && imnmx.dest_reg == shl_reg;
+ });
+}
+} // Anonymous namespace
+
+std::optional<IndirectBranchTableInfo> TrackIndirectBranchTable(Environment& env, Location brx_pos,
+ Location block_begin) {
+ const u64 brx_insn{env.ReadInstruction(brx_pos.Offset())};
+ const Opcode brx_opcode{Decode(brx_insn)};
+ if (brx_opcode != Opcode::BRX && brx_opcode != Opcode::JMX) {
+ throw LogicError("Tracked instruction is not BRX or JMX");
+ }
+ const IR::Reg brx_reg{Encoding{brx_insn}.src_reg};
+ const s32 brx_offset{static_cast<s32>(Encoding{brx_insn}.brx_offset)};
+
+ Location pos{brx_pos};
+ const std::optional<u64> ldc_insn{TrackLDC(env, block_begin, pos, brx_reg)};
+ if (!ldc_insn) {
+ return std::nullopt;
+ }
+ const LDC::Encoding ldc{*ldc_insn};
+ const u32 cbuf_index{static_cast<u32>(ldc.index)};
+ const u32 cbuf_offset{static_cast<u32>(static_cast<s32>(ldc.offset.Value()))};
+ const IR::Reg ldc_reg{ldc.src_reg};
+
+ const std::optional<u64> shl_insn{TrackSHL(env, block_begin, pos, ldc_reg)};
+ if (!shl_insn) {
+ return std::nullopt;
+ }
+ const Encoding shl{*shl_insn};
+ const IR::Reg shl_reg{shl.src_reg};
+
+ const std::optional<u64> imnmx_insn{TrackIMNMX(env, block_begin, pos, shl_reg)};
+ if (!imnmx_insn) {
+ return std::nullopt;
+ }
+ const Encoding imnmx{*imnmx_insn};
+ if (imnmx.is_negative != 0) {
+ return std::nullopt;
+ }
+ const u32 imnmx_immediate{static_cast<u32>(imnmx.immediate.Value())};
+ return IndirectBranchTableInfo{
+ .cbuf_index = cbuf_index,
+ .cbuf_offset = cbuf_offset,
+ .num_entries = imnmx_immediate + 1,
+ .branch_offset = brx_offset,
+ .branch_reg = brx_reg,
+ };
+}
+
+} // namespace Shader::Maxwell